What they do: Online retail, storefronts for small businesses and enterprise-class cloud computing

Disruptive qualities: Amazon tripled revenues in the past six years with innovations that include adding outside vendors to its marketplace and perfecting digital book, music and movie delivery. Now, Amazon is distributing the keys to its technology kingdom by opening its massive infrastructure to innovative startups that use Amazon Web Services’ pay-as-you-go computing power and storage to handle their computing and storage needs.

The tech that makes them tick: For Amazon’s Web services, it’s all about heft: a $2 billion infrastructure in the form of 10,000 distributed servers, along with standards-based REST and SOAP interfaces designed to work with any Internet-development tool kit.

Who they are disrupting: Amazon used to threaten only book and record stores, but now it’s going after everyone who sells on-site IT infrastructure, not to mention the other emerging cloud-computing players such as IBM and Sun Microsystems. Can Salesforce.com and Microsoft Live be far behind?

Bungle in the jungle? Amazon Web Services has had its share of growing pains, including an outage of its Simple Storage Service (S3) hosted storage in February, which brought down thousands of startups for the better part of a day. Reliability of Web-based services can be difficult.